OYSTER BOTTOMS OF MISSISSIPPI EAST OP BILOXI. 33 



In view of these facts and probabilities, and the present impossi- 

 bility of establishing a standard for the expression of the quantity 

 of food available, the data respecting the food content of the water 

 collected during this survey will not be stated here. A special paper 

 on the entire subject of the food and feeding of oysters will be issued 

 on the completion of the studies. 



It may be stated from observation of the oysters and on general 

 grounds that the food supply in Mississippi Sound and minor con^ 

 tiguous waters is ample. 



OYSTER ENEMIES. 



As the survey was carried on durmg the early spring, when the 

 water was still comparatively cold, the observations made are prob- 

 ably not to be regarded as a reliable index to the abundance of oyster 

 enemies. None were observed but a few drills, mostly small, and an 

 insignificant number of mussels. The low temperature of the water 

 could have had but little effect on the latter, and it is fair to assume 

 that ordinarily they are nowhere present in sufficient numbers to 

 prove seriously detrimental to the oysters. 



As observations on other parts of the Gulf coast have sho^vn that 

 certain enemies to the oyster are of general occurrence, it appears 

 advisable to furnish some general information respecting them. 



Drill, horer, snail, whelk, conch {Purpura lixmostoma) . — This animalj 

 which bears these several names on the Gulf coast, was found very 

 sparmgly during the survey in Mississippi waters, and there was 

 little other indication of its presence. A few small ones were taken 

 on Scranton Reef and in Biloxi Bay, but in neither place was there 

 found a sufficient number of drilled oyster sheEs to indicate that it 

 had been recently abundant. It is liable to occur, however, espe- 

 cially in the more saline water, and care should be exercised not to 

 introduce it with seed oysters from infested beds. 



The drill or whelk lays its eggs in red or purple leathery capsules 

 about one-half inch long and attached in clusters to sheUs, snags, and 

 other firm bodies in the water. The young become destructive to 

 the minute spat immediately upon emerging from the egg cases; they 

 grow rapidly and progress in destructiveness as they mcrease in size. 

 They destroy the oysters by drilling a small round hole through the 

 shell, usmg for the purpose a flexible rasp-like organ lying at the end 

 of a protrusible proboscis. After the shell is perforated the proboscis 

 is thrust into the shell and the contents eaten, other drills sometimes 

 partaking of the feast by entering the gaping shell of the dead or 

 dying 05^ster. !Most of the oysters destroyed are under 2 inches long, 

 but large drills often kill more adult oysters. 



Mussels. — The common black sea mussel is a passive enemy of 

 oysters, through its tendency to attach to them and under favorable 



